Short for British Thermal Unit, British standard unit of energy. One Btu is equal to the amount of heat required to raise the temperature of one pound of liquid water by 1 degree Fahrenheit at its maximum density, which occurs at a temperature of 39.1 degrees Fahrenheit.

One Btu is equal to approximately 251.9 calories or 1055 joules.

Now choose your Radiator

How do you know what size of radiator you need in your room?

Radiators have become more efficient in the last 10 years, giving off more heat for the same physical height and width. So when replacing a radiator in a bedroom, bathroom or kitchen, you might not need the same physical size of radiator you had there before. You don't want to under-estimate your heat requirements, either. It would be horrible to get out of the shower and shiver!

Radiators are constructed in different ways which affect the heat they can give off. This is down to things like the amount of surface area, the flow of the hot water through the radiator, how the radiator convectors are joined to the radiator, or even if they have them at all! So, radiators aren't about size, they're about the amount of heat they give off.

And the clever people have kindly worked out a mathematical formula for figuring out what output of radiator you'll need in each room of your house. All you have to do is answer the questions, then hit the calculate button.

The formula takes into account the size of the room, what it's used for and how much extra heat loss happens because of large windows, being on the cold side of the house and whether or not you have double glazing.

Once you've calculated the number of BTUs you need for the room, we've made it easy for you to find the radiator you need - just click on the type you want - a towel rail, a standard panel radiator, or something a little bit special - a designer radiator. Our special system will take you to all the radiators that will be suitable for the heat output you need for your room.

BTU Calculator

Ever wondered how the experts calculate exactly which size radiator you’ll require to effectively heat your property? Trade Plumbing has made it incredibly easy for you to discover the exact specifications required to heat or cool any room in your home. Check out our easy-to-use BTU calculator – it’ll quickly let you know the number of BTUs you need for each individual room, allowing you to choose a radiator with a suitable output!

The phrase ‘BTU’ stands for British Thermal Unit, which is a standard unit of energy equal to approximately 1,055 joules (or 251.9 calories).

BTU Radiator Calculator

Using an intelligent mathematical formula and taking a number of different factors into consideration, our BTU calculator can tell you straightaway the output of radiator you’ll need for every single room in your home. While it’s important that your house is heated comfortably, you want your choice of radiator to remain as energy efficient as possible if you’re to avoid unnecessarily high heating costs. When it comes to the size of the radiator itself, it’s also important to remember that there has been much technological advancement in the last couple of decades that has resulted in the development of smaller units that are able to give off a great deal of heat. The results of our BTU radiator calculator will allow you to explore your options - you may even find that you don’t need to install a big, bulky radiator at all and will achieve similar results with the use of a smaller unit.

Watts to BTU Calculator

To start using our BTU radiator calculator, you’ll need to gather together the dimensions of each room in the question, specifically its width, length and height, and tell us whether it’s a dining room, bedroom, bathroom, kitchen or lounge – each kind of room typically has its own needs. It’s also best to tell us whether the room has large windows or a north facing wall, as these may affect how well the room insulates heat. This is because north facing walls generally receive maximum winter sun and warmth yet are notoriously colder during other months, resulting in a significant amount of heat loss throughout the year. You’ll also need to tell the BTU radiator calculator if your room. These conditions need to be factored into the equation if you’re going to generate accurate results from the watts to BTU calculator.